Camrelizumab Plus Risedronate and Chemotherapy for Triple-Negative Breast Cancer: An Exploratory Clinical Study on Mechanisms and Efficacy

Inclusion Criteria:

1. Female patients aged ≥ 18 years and ≤ 70 years.
2. Histopathologically confirmed triple-negative breast cancer: Immunohistochemistry (IHC) shows estrogen receptor (ER) and progesterone receptor (PR) are both negative (i.e., positively stained tumor cells account for \<10% of all tumor cells); IHC shows HER2 negative: test result is 0/1+; if the test result is 2+, in situ hybridization (ISH) must show a HER2/CEP17 ratio \< 2.0 or HER2 gene copy number \< 4.
3. Presence of measurable tumor lesions (meeting RECIST 1.1 criteria).
4. ECOG performance status score of 0-2.
5. Life expectancy of no less than 3 months.
6. Adequate major organ function meeting the following criteria (no blood transfusions, no use of leukocyte- or platelet-raising drugs within 2 weeks prior to screening):

(1) Hematology requirements: ANC ≥ 1.5 × 10⁹/L; PLT ≥ 90 × 10⁹/L; Hb ≥ 90 g/L. (2) Biochemistry requirements: TBIL ≤ 1.5 × upper limit of normal (ULN); ALT and AST ≤ 1.5 × ULN; Alkaline phosphatase ≤ 2.5 × ULN; BUN and Cr ≤ 1.5 × ULN and creatinine clearance ≥ 50 mL/min (by Cockcroft-Gault formula).

(3) Thyroid-stimulating hormone (TSH) ≤ ULN (if abnormal, T3 and T4 levels should be checked; patients with normal T3 and T4 levels can be enrolled).

(4) Cardiac color Doppler ultrasound and echocardiography: Left ventricular ejection fraction (LVEF) ≥ 50%.

(5) 18-lead ECG: Fridericia-corrected QT interval (QTcF) \< 480 ms for females.

7.Women of childbearing potential must have a negative pregnancy test (serum or urine) within 7 days before enrollment and voluntarily agree to use adequate contraception during the observation period and for 4 months after the last dose of the study drug.

8.Voluntary participation, signed informed consent, and good compliance.

Exclusion Criteria:

1. Concurrently receiving anti-tumor therapy in another clinical trial.
2. Received other anti-tumor therapy within 14 days prior to the first dose.
3. Underwent major surgery unrelated to breast cancer within 4 weeks before enrollment, or has not fully recovered from such surgery.
4. Patients with any active autoimmune disease or a history of autoimmune disease (such as, but not limited to: autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, hypothyroidism; patients with vitiligo or childhood asthma that has completely resolved and requires no intervention in adulthood may be included; patients requiring bronchodilators for asthma management cannot be included).
5. Severe cardiac disease or discomfort, including but not limited to: history of heart failure or systolic dysfunction (LVEF \< 50%); high-risk uncontrolled arrhythmias, such as atrial tachycardia, resting heart rate \> 100 bpm, significant ventricular arrhythmias (e.g., ventricular tachycardia), or higher-degree atrioventricular block (i.e., Mobitz II second-degree or third-degree AV block); angina requiring anti-anginal medication; clinically significant valvular heart disease; ECG evidence of transmural myocardial infarction; poorly controlled hypertension (systolic blood pressure \> 180 mmHg and/or diastolic blood pressure \> 100 mmHg).
6. Patients with congenital or acquired immunodeficiency (e.g., HIV infection).
7. Received a live vaccine within 4 weeks prior to study medication or plans to receive one during the study.
8. Inability to swallow tablets, malabsorption syndrome, or any condition affecting gastrointestinal absorption.
9. Known history of allergy to any component of the study drugs in this protocol.
10. Patients with hypocalcemia.
11. Patients unable to maintain a standing or sitting upright position for 30 minutes.
12. Presence of severe concomitant diseases or other comorbidities that would interfere with the planned treatment, or any other condition deemed by the investigator to make the patient unsuitable for participation in this study.